CAREER: Resolving a paradox of global botanical biodiversity: why is Africa the "odd man out?"

自达尔文时代以来，了解植物多样性是如何随着时间的推移而产生的，以及植物是如何以及为什么在地球上分布的，一直是生物多样性科学的主要目标。全球植物分布的一个特别显著的特征是，撒哈拉以南非洲的植物种类比亚洲和美洲的可比热带地区少得多，这被称为“异类”生物地理格局。这项研究将通过调查蕨类植物的进化史来调查这种“异类”模式的可能原因。蕨类植物是一种古老的植物群，在全球范围内占据着多种生态系统。因此，它们是了解灭绝、物种形成和迁徙在撒哈拉以南非洲现代植物群形成过程中所起作用的理想模型。该项目的广泛影响将建立包括博士后研究员、佛罗里达大学研究生和本科生在内的早期职业科学家的研究能力，并在不同的K-12和大学教室中加强生物多样性科学教育。项目人员将在南部非洲开设一门出国留学本科课程，让中学教师参与制定K-12课程计划，并为植物和生物多样性科学的公众宣传建立网络和实践模块。研究人员将揭示分布在非洲、亚洲和美洲大陆的三种蕨类植物的进化和生物地理历史，以调查“异类”生物地理格局的起源。物种将在野外和植物标本室取样；来自大约450个核标记的DNA序列数据将用于生成它们的系统发育。由此产生的系统发育将用于重建1000多个物种的历史生物地理运动，计算多样化率，并确定祖先生态位包膜的变化是否与迁移事件或多样化率的变化相关。祖先气候重建和来自普通花园实验的特征数据将共同分析，以了解气候如何随着时间的推移塑造特征和多样化模式。该项目将为广泛传播和建立跨机构合作提供新的数据资源和样本。这些成果将推进研究，并为蕨类植物系统学、历史生物地理学和生物多样性科学交叉领域的未来发现提供燃料。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding how plant diversity has arisen over time, and how and why plants are distributed across the planet as they are, has been a major goal of biodiversity science since Darwin's time. A particularly striking feature of global plant distributions is that sub-Saharan Africa has many fewer plant species than comparable tropical regions in Asia and the Americas, which is known as the "odd man out" biogeographic pattern. This research will investigate the possible causes of the odd man out pattern by investigating the evolutionary history of ferns. Ferns are an ancient plant group that occupy diverse ecosystems globally. Consequently, they are ideal models for understanding the roles of extinction, speciation and migration in generating the modern-day flora of sub-Saharan Africa. Broader impacts of the project will build research capacity among early career scientists, including post-doctoral fellows, graduate and undergraduate students at the University of Florida and strengthen biodiversity science education within diverse K-12 and college classrooms. Project personnel will develop a study-abroad undergraduate course in southern Africa, engage middle school teachers in developing K-12 lesson plans, and build both web-based and hands-on modules for public outreach about plants and biodiversity science. Researchers will uncover the evolutionary and biogeographic history of three fern genera (Dryopteris, Cheilanthes, Polystichum) that are widespread in African, Asian and the American continents to investigate the genesis of the odd man out biogeographic pattern. Species will be sampled in the field and from herbaria; DNA sequence data from approximately 450 nuclear markers will be used to generate their phylogenies. The resulting phylogenies will be used to reconstruct historical biogeographic movements of over 1000 species, calculate diversification rates, and determine whether shifts in ancestral ecological niche envelopes correlate with migration events or changes in diversification rate. Ancestral climate reconstructions and trait data from common garden experiments will be co-analyzed to understand how climate may have shaped traits and diversification patterns over time. The project will generate new data resources and specimens for broad dissemination and build cross-institutional collaborations. These outcomes will advance the research as well as fuel future discoveries at the intersection of fern systematics, historical biogeography and biodiversity science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.